1. Field of the Invention
The present invention relates to a dual-type organic electroluminescence (EL) display and a manufacturing method thereof, and, more particularly, to a dual-type organic electroluminescence display having an improved connection structure of a flexible printed cable electrically connected to terminals provided at main and sub organic EL displays and an improved driving method, and a manufacturing method thereof.
2. Description of the Related Art
In general, organic EL displays are spontaneous light-emitting display devices which emit light through electrical excitation of fluorescent organic compounds, and provide various advantages including a low drive voltage and thin film formability. Also, organic EL displays are attracting much attention as next-generation display panels, since they provide a wide viewing angle, a fast response time, and so on.
An organic EL display operates as follows. When power is supplied, electrons migrate and current flows. At a cathode, electrons migrate to a light-emitting layer through an electron transport layer. At an anode, holes migrate to the light-emitting layer through a hole transport layer. The electrons and holes migrating to the light-emitting layer generate excitons having high energy. The excitons are deactivated to a ground state and thus light is emitted. Full color display can be achieved according to the kinds of an organic material forming the light-emitting layer.
Recently, users have desired dual type organic EL displays capable of simultaneously displaying two images in a folder type electronic device. The structure of the dual-type organic EL display is well known in Japanese Patent Application Laid-Open Nos. hei 10-255974, 2000-58260 and 2001-332392.
FIG. 1 shows a conventional dual type organic EL display.
Referring to FIG. 1, the dual-type organic EL display includes a main organic EL device 10 and a sub organic EL device 100.
The main organic EL device 10 includes a substrate 11, an organic light-emitting portion 12 formed on the substrate 11, a cap 13 protecting the organic light-emitting portion 12, a moisture absorbent 14 installed in the cap 13 and a polarizing plate 15 installed in front of the substrate 11.
The sub organic EL device 100 connected to the main organic EL device 10 has substantially the same structure as that of the main organic EL device 10, and includes a substrate 110, an organic light-emitting portion 120, a cap 130, a moisture absorbent 140 and a polarizing plate 150.
In order to allow a user to selectively look at two displays in different directions indicated by arrows, the dual-type organic EL display has the sub organic EL device 100 connected to the rear surface of the main organic EL device 10.
For example, folder-type electronic devices can utilize external panel information directly displayed on a window without special manipulation just by employing a dual-type display device, and can utilize panel information displayed on another window by simple manipulation.
A process of manufacturing the dual-type organic EL display having the above-described configuration will now be briefly described.
A substrate 11 for the main organic EL device 10 is first provided. An organic light-emitting portion 12, including an anode, an insulator layer, an organic layer and a cathode, is then patterned on the substrate 11. A cap 13 for protecting the resultant structure is mounted, and a polarizing plate 15 is attached to the front surface of the substrate 11. In order to remove moisture generated in a sealed space, a moisture absorbent 14 is provided inside the cap 13.
Also, on a substrate 110 for the sub organic EL device 100, an organic light-emitting portion 120, a cap 130 provided with a moisture absorbent 140, and a polarizing plate 150 are mounted.
Next, the main and sub organic EL devices 10 and 100 are connected to each other in a state in which display portions are opposite to and face each other.
In the respective substrates 11 and 110 of the main and sub organic EL devices 10 and 100, electrode lines having a predetermined pattern are formed.
FIG. 2A shows electrode lines of the main organic EL device 10 shown in FIG. 1, and FIG. 2B shows electrode lines of the sub organic EL device 100 shown in FIG. 1.
Referring to FIGS. 2A and 2B, strip-shaped main substrate scan lines 21 and strip-shaped main substrate data lines 22 crossing the main substrate scan lines 21 are arranged on the substrate 11 for the main organic EL device 10, the respective lines spaced a predetermined distance from each other. The main substrate scan and data lines 21 and 22 are electrodes of the organic light-emitting portion 12. Strip-shaped sub substrate scan lines 210 and strip-shaped sub substrate data lines 220 parallel to the sub substrate scan lines 210 are arranged on the substrate 110 for the sub organic EL device 100, the respective lines spaced a predetermined distance from each other. The sub substrate scan and data lines 210 and 220 are grouped at a first side of the substrate 110.
Flexible printed cables (FPCs) are connected to the main and sub organic EL devices 10 and 100, having the respective electrode lines, applying external power, as shown in FIGS. 3A and 3B.
As shown in FIG. 3A, the main substrate scan lines 21 and the main substrate data lines 22 are arranged at two sides of the substrate for the main organic EL device 10. An FPC 31 for the main substrate scan lines 21 and an FPC 34 for the main substrate data lines 22 are connected to the main substrate scan and data lines 21 and 22, respectively.
Interconnections 32 for the main substrate scan lines 21 and interconnections 35 for the main substrate data lines 22 are patterned in the FPCs 31 and 34, respectively, and at least one drive chip 33, 36, driving both the main substrate scan and data lines 21 and 22, is provided.
As shown in FIG. 3B, the sub substrate scan lines 210 and the sub substrate data lines 220 are drawn to a first side of the substrate 110 for the sub organic EL device 100, and a sub substrate FPC 37 is connected to the sub substrate scan lines 210 and the sub substrate data lines 220. Sub substrate interconnections 38 are patterned in the sub substrate FPC 37, and a drive chip 39 for driving both the sub substrate scan and data lines 210 and 220 is disposed at the sub substrate FPC 37.
The conventional dual-type organic EL display has the following problems.
First, the caps 13 and 130, incorporating the respective moisture absorbents 14 and 140, are installed at a connected portion of the main organic EL device 10 and the sub organic EL device 100. The heights of the caps 13 and 130 are combined, resulting in an increase in the overall thickness of the dual-type organic EL display. Therefore, since there is a limitation in thinning, satisfactorily lightweight, miniaturized electronic devices cannot be obtained.
Second, since the FPCs 31 and 34 connected to the main substrate scan and data lines 21 and 22 of the main organic EL device 10, the drive chips 33 and 36 mounted thereon, the sub substrate FPC 37 connected to the sub substrate scan and data lines 210 and 220 of the sub organic EL device 100, and at least one drive chip 39 mounted on the FPC 37, are all necessary, the design of the drive chips 33, 36 and 39 is complicated, resulting in an increase in cost.